Grinding machine



`une 20, 1961 GRINDING MACHINE Origmal Filed Nov. 29, 1956 BAss Er AL 2,988,858

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GRINDING MACHINE Origmal Filed Nov. 29, 1956 8 Sheets-Sheet 6 1 lll H TTRNE YS June 20, 1951 M. M. BAss ErAL 2,988,858

GRINDING MACHINE Origlnal Filed Nov. 29, 1956 8 Sheets-Sheet 7 June 20, 1961 M. M. BAss ErAL 2,988,858

GRINDING MACHINE origmal Filed Nov. 29, 1956 a sheets-sheet e niteci States Patnt V2,988,858 Patented June 2Q, 19.61

2,988,858 GRINDING- MACHINE Miles M. Bass, Kalamazoo, Ramsay M. Bell, Schoolcraft, Lee 'C. Hammond, Kalamazoo, Edward '(1. Krueger, Otsego, and Philip J. Robischung, Kalamazoo, Mich., assignors to Hammond Machinery Builders, Inc., Kalamazoo, Mich., a corporation of Michigan Continuation of application Ser. No. 625,009, Nov. 29, 1956. This application May Z0, 1959, Ser. fNo. 814,486 12 Claims (Cl. 51-55) This invention relates to a tool grinder and particularly to a combined work holding, work positioning and work feeding means therefor which may be readily adapted by the operator to be fully automatic, semi-automatic or manually operated according to the type of service to be performed. This application is a continuation of our copending yapplication Serial No. 625,009, led November -.29, 1956.

In spite of constant and serious attempts to improve the machinery used for grinding various types of cutting tools, relatively little success has been achieved in the development of an automatic, or substantially automatic, machine for grinding large numbers of identical tools. This appears to be Idue in part to lthe .ditliculty of rendering the tool holding mechanism of an automatic machine sutficiently flexible to handle a wide variety of types of tools and also capable of manual operation when the need arises. It is known that, under any circumstances, there are always a few tools which do not lend themselves readily to automatic grinding either because of their peculiar shape or because of their limited number. Thus, at least from a commercial point of View, the result has usually been that, since a few tools must almost always be handled individually and, therefore, a skilled grinding operator is necessarily present anyway for handling such individual tools, there is insuicient economy to be obtained by having an automatic machine in addition to a separate manually controlled machine. Because of this, a great amount Vof time is lost, particularly by manually holding and controlling large numbers of identical tools which must receive the same grinding operation.

Accordingly, a major object of the present invention has been the provision of work holding means particularly intended for tool grinding but applicable to other grinding purposes as well, and which at the will of the operator may be readily arranged to operate as a fully automatic machine, as a semi-automatic machine or by solely manual positioning and control of the tool.

A further object of the invention has been to provide a machine, as aforesaid, in which thesteps required to convert the machine from any one to any other of fully automatic, semi-automatic or manually controlled conditions can be carried out easily and quickly and can normally be carried out -by the machine operator himself.

A further object of the invention has been to provide a machine, as aforesaid, which (a) when operated as an automatic machine and With any selected adjustment is capable of handling large quantities of identical tools, and (b) is capable of adjustment to adapt it for `handling a wide variety of shapes and sizes of cutting tools.

A further object of the invention has been to provide a machine, as aforesaid, which will be provided with means for `f ully protecting the wheel from damage in the event of improper setting of the automatic driving mechanism.

A further object of the invention has been lto provide a machine, as aforesaid, having workhandling kmechanism which will be adaptable to cooperation with an oscillating grinding-wheel, which is not unduly complex and -which will ,accordingly not mvolve either unreasonable original expense orunreasonable maintenance costs.

A further object of the invention has been to provide a machine, as aforesaid, in which the work handling mechanism includes a work holding device and =a Work feeding device which are independent of each other in order that the work may be mechanically held but manually fed where desired. Y

A further object of the invention has been to provide a machine, as aforesaid, which can be readily operated -by any operator accustomed to grinding tool tips on conventional grinders.

A further object of the invention is to provide a machine, as aforesaid, which will be readily adjustable ',to exercise a precise and automatic control over the amount of material removed by the grinding operation.

Other objects and purposes of the invention will be apparent to persons acquainted with apparatus of this general type upon a reading of the following specication and inspection of the accompanying drawings, in which:

FIGURE 1 is a front elevational view of the upper portion of a tool grinding machine embodying the invention.

FIGURE 2 is a sectional view of said tool grinding machine substantially as taken along the line IIII of FIGURE 1.

FIGURE 3 is a sectional view taken along the line III-III of FIGURE 1.

FIGURE 4 is a sectional view substantially as taken along the line IV-IV of FIGURE .1.

FIGURE 4a is an enlarged, detailed view of a fragment of FIGURE 4.

FIGURE 5 is a sectional view taken along the line V-V of FIGURE 4.

FIGURE 6 is a sectional view taken along the line VI-VI of FIGURE 5.

FIGURE 7 is a sectional view substantially as `taken along the line VII- VII of FIGURE 4.

FIGURE 8 is a sectional view substantially as taken along the line VIII--VIII of FIGURE 4.

FIGURE 9 is a sectional view taken along the line IX-IX of FIGURE 4.

FIGURE l0 is a sectional view substantially as taken along the line X--X of FIGURE 4, rotated clockwise and showing a modified, table actuating device.

FIGURE 11 is a fragmentary, top plan view of the structure shown in FIGURE 3, and including :an adjustable tool holder.

FIGURE l2 .is a sectional view taken along the line XII- XII of FIGURE 11, and rotated 90 clockwise.

FIGURE 13 is a sectional view of said tool holder taken along the line XIII- XIII of FIGURE ll.`

FIGURE 14 is a broken, sectional view taken along the line XIV- XIV `of FIGURE 13.

FIGURE 15 is a sectional view taken along the line XV-XV of FIGURE 13. f

FIGURE 15a is a sectional view taken along the line XVa--XVa of FIGURE 13 with the eccentrichwb removed.

FIGURE 16 is a plan View of the tool holder substan; tially as shown in FIGURE ll, but 4arranged in a different position.

l FIGURE 17 `is a sectional view XVII-XVII of FIGURE v13. j

FIGURE 18 is a sectional `view taken along the line XVIII- XVIII of FIGURE 17 and ,rotated 90 clockwie and including'a portion of the work supporting ta le.

FIGURE 19 is a fragmentary, `top Vplan view yof the structure `shown in FIGURE ll, and including a tool positioning device. Y

FIGURE 20 is a broken sectional view taken along the line XX--XX of FIGURE 19.

taken along the line 21 is asectional view taken along the line )QUI-XXI of FIGURE 19.

FIGURE 22 is a sectional view taken along the line XXII- XXII of FIGURE 19 and rotated 90 counterclockwise.

i' FIGURE 23 is a fragment of FIGURE 19 with parts thereof in different operating positions.

I For purposes of convenience in description, the terms front, rear, upper, lower, left, right, and derivatives thereof, will have reference to the grinding machine in its normal position of operation. More specifically, front will have reference to that side of the machine appearing in FIGURE l, which is the side normally facing the operator. Similarly,the terms vertical, ,horizontaL derivatives thereof, and other words importing' position, will be freely used for convenience in reference and will be understood to refer to-the struc- Lture as shown andin its position of normal use. However, the use of such terminology shall not imply that'the structure cannot be used in other positions, nor shall it implythat the principles of the invention, as hereinafter defined, cannot be employed in modified structures havingother and differing positions of normal use.

GENERAL DESCRIPTION In general, the apparatus of the present invention is normally, though not necessarily, embodied in a machine having a radially reciprocating grinding wheel of the type 'set forth in Patent No. 2,922,258, dated January 26, 1960. The machine ofthe present invention-includes a table whichis reciprocableA toward and away from the face of said grinding wheel in a direction parallelwith the axis of 'said grinding wheel, said table being provided with a removable holding device for rmly and adjustably holdingy the workpiece, normally a cutting tool, in a precisely predeterminable position with respect to the face of the grinding wheel. A positioning device, which is -cooperable with both the table and the work holding device, is provided for quickly and accurately positioning a group of substantially identical tools, upon which the same operation is to be performed, within and with respect to said holding device. Anactuating device, such as a pressure cylinder, is, in the fully automatic arrangement, mounted between the frame of the machine and the table for urging the tabletwardfand away from the grinding-wheel in said above-designated direction. An adjustable control is provided forterminating the grinding operation by stopping such urging when the table reaches a predetermined position corresponding to the desired amount of grinding. Said control then returns the table to its initial position. Positive, adjustable stops determine. the maximum movement'of the table and protect both the table and the grinding wheel from damaging interference with each other in the event of failure of the adjustable control.

Where the machine isi-to be operated semi-automatically, lthe actuating device is replaced by resilient means which continuously urges the table away from the grinding wheel, the table being vmanually urged toward the grinding ,wheel. Where the tool to be ground is to be held entirely manually, the table is fixed in a selected position, usually closely adjacent to the grinding wheel, by a. suitable brake and the work holding device is removed. Thel wheel, however, continues to oscillate as before so that the tool being ground still needs to be held only in one selected position on the table against the rotating and radially oscillating grinding wheel.

DETAILED CONSTRUCTION General organization More specifically, and as shown in FIGURES l and 2, the tool grinding machine has a support frame 11 with av top plate 12, upon which is supportedY the pivot structure 13, which pivotally and rotatably supports the spindle 14. A grinding wheel is mounted upon thefront end of the spindle 14 (FIGURES 2 and 3) for rotationby said spindle and radial oscillation in a substantially horizontal direction by the pivot structure 13. The pivot structure 13, the grinding wheel 15 and the mechanism within the frame 11 for effecting controlled oscillation and rotation of the grinding wheel 15 through the pivot structure 13 are completely disclosed and discussed in Patent No. 2,922,258. Thus, further detailed description of these elements of the grinding machine 10 is believed to be unnecessary.

A table base 16 is mounted upon the forward end of the support frame 11 for horizontal movement in a direction substantially parallel with the axis of the spindle 14. A hood 17, which surrounds the grinding wheel 15, is provided with a bottom wall 18, which is supported upon the table base 16. A pair of table support members 20 and 21 (FIGURES 1, 2 and 3) are mounted upon the bottom wall 18 of the hood on radially opposite sides of the grinding Wheel 15. Said support members may be, and preferably are, substantially identical to the support members disclosed in Patent No. 2,922,258. Thus, they are arranged to effect a tilting of the work table 22 about a substantially horizontal axis 23 defined by the edge of the upper surface 24 of said table adjacent to the grinding wheel 15. The table support members 20 and 21, as well as the hood 17, are held in position with respect to the table base 16 by means of the bolts 25, which extend through the table support flanges 40 and 41 on the base 16 and said bottom wall 18 into said members.

Table recprocable support A pair of base support bars 30 and 31 (FIGURES 4 andy 9)l are supported at their rearward ends upon the frontend of the top plate 12 of the frame 11 and extend substantially horizontally therefrom in parallel relationship with respect to each other. Said bars are given additional support with respect to the support frame 11 by means of the gussets 32 and 33, which are secured to, and extend forwardly from, said frame 11 under said bars 30 and 31. The mutually remote or outer lateral sides of the support bars 30 and 31 are provided with elongated, parallel and horizontal recesses 34 and 35, respectively. A pair of guide ways 36 and 37 are removably held within the recesses 34 and 35 by means of the set screws 38. Said guide ways 36 and 37 are provided with parallel, horizontal grooves 50 and 51 along the respectively outer surfaces thereof.

The table base 16 (FIGURE 9) is a substantially rectangular, relatively flat member, having a pair of outwardly extending, substantially co-planar table support fianges 40 and 41. Said base 16 is superimposed in broken lines at 16b in FIGURE 4 to show its relation with the parts disposed below said base. The base has a pair of parallel base support flanges 26 and 27 (FIGURES 4 and 9), which extend downwardly from the table support flanges 40 and 41. Said fianges 26 and 27 are positioned along, and spaced from, the said outer surfaces of the support bars 30 and 31, respectively. A pair of parallel, elongated recesses 42 and 43 are provided in the opposing faces of the flanges 26 and 27, respectively, near, and substantially parallel with, the lower edges thereof. A pair of elongated guide ways 44 and 45 (FIGURES 5, 6 and 9), which may be identical to the guide ways 36 and 37, are removably held within said recesses 42 and 43 by means of set screws 46. The opposing sides of the guide ways 44 and -45 are provided with parallel grooves 47 and 48, respectively.

A plurality of bearing balls 52 (FIGURES 4 and 9), are disposed between the guide ways 44 and 36, and 45 and 37, within their respective grooves. The said guide ways 44, and 45, 36 and 37, and their corresponding grooves, are so arranged that the table base 16 is supported upon the base support bars 30 and 31 entirely by the bearing balls 52, with the center plate 53 of the table base 16 extending between the flanges 40 and 41 above said support bars 30 and 3|1.' A plurality of adjustment studs 54 (FIGURES 5 and 6) are threadedly received -a-asass -hcre the leftward, surface 5510i the guide way 44, whereby said guide way 44 may be adjustably urged inwardly, or rightwardly, with respect to said flange 26. Because of the free-floating nature of the mounting of the table `base 16 upon the support .bars 30 and 31, such .rightward `movement of the guide way 44 produces the total reifect of causing all four of the guide ways 44, 45, 36 and 37 to snugly embrace the bearing balls 52 disposed therebetween. Look nuts 56 are provided on the studs 54- for holding the adjustment thereof.

End plates, such as those shown at 57 and 58 in FIGURE 6, are secured, as by means of the .screws 59, upon the front and rear ends of the said guide ways to retain the bearing balls 52 within the corresponding grooves in said guide ways when they are moved relative to each other. Inasmuch as the movement between the walls of said grooves and the bearing balls -5-2 is a rollingtype movement, 4the centers of said bearing balls will move only one-half of the relative distance moved by the guide ways. Accordingly, the grooves 47, `48, 50 and 5-1 are substantially illed un'th bearing balls 52, there being only enough unoccupied space in said grooves to permit a relatively short movement, such as approximately one inch, of the guide ways 44 and 45 with respeot to the guide ways 36 and 37. Thus, there are adequate bearing balls within said grooves to provide the lnecessary support of the table base 16 upon the base support bars 30 and 311.

The extent of the forward and rearward movement of said table base 16 with respect to the support bars 30 and 31 is not necessarily equal to the amount of movement permitted by the quantity of bearing balls 52 within the grooves or races in said guide ways. As shown `in FIGURES 4, 7 and 8, adjustable stop Vor limit devices 61 and 62 are provided at the forward ends of the base support bars 3i! and 31, respectively, for selectively controlling absolutely the full fonward and full 4rearward positions of the table base 16 with respect to the support bars 30 and 31. The rearward motion limit device 62 (FIGURES 4 and 8) is comprised of a forwardly `extending bracket 63` secured tothe front edge of the table base 16, by means such as the machine screw 64, and having a downwardly extending flange 66. An adjustment bolt 65 is threadedly received through the flange 66 for engagement with the forward end of the right support bar 31. Thus, rearward movement of the bracket 63, hence the 4table base 16, is adjustably limited by engagement between the bolt 65 and the adjacent end of the support bar 31. l

The forward motion limit device 61 (FIGURES 4 and 7), which controls the frontward movement of the table base 16 with respect to the grinding wheel 15, is comprised of an upwardly extending bar 67 secured, as by means of the machine screw 68, upon the front end of the left support bar 30. An adjustment bol-t 69 is threadedly received through the upper end of the bar .67 and extends toward, and is engageable with, the adjacent, front edge of the table base 16. When said table base 16 is in a selected fully frontward position, as indicated in broken lines at 16a in FIGURE 7, the adjustment bolt 69 engages the adjacent edge of said table base and prevents further frontward motion.

As shown in FIGURES l and 4, the table base 16 has a frontward projection 71 disposed between the limit devices 61 and 62 and having a downwardly extending arrn 72 at the frontword end thereof. The projection 71, as well as the center plate 53- (FIGURE 9) which extends rearwardly from said projection 71, is upwardly arched to form a cavity 73. An actuating device, such as the power cylinder 74, is disposed within the cavity 73, with its piston rod 75 pivotally secured to the lower end of the arm 72 (FIGURES l and 4). The rear end of the cylinder 74 is pivotally secured to the bracket 76 which is mounted upon the top `plate 12 of the support frame 11. Thus, reciprocation of the table base 16 can be eifeoted by extension and lretraction of the piston rod 75 vw'thin the power cylinder 74. The opposite ends of the power cylinder 74 are provided with conduits 77 and 78, by means of which a source 79 of pressure Vfluid (FIGURES 4 and 4a) is connected through Ithe control valve 80 to the cylinder 74 in a substantially conventional manner.

An electric switch 81 (FIGURES 4 and 4a) is mounted upon the top plate 12 of the frame 11 near to, but spaced from, the rearward and rightward end of the table base 16. Said switch -is connected in a conventional manner to the control valve 80 associated with the source 79 of pressure iiuid, for the purpose of operating said valve 80 and thereby reversing the ow of said fluid from said source upon actuation of said switch. Said switch is operated by a plunger 82 extending frontwardly therefrom between a pair of parallel, upstanding guard Ibars 83 and 84. A switch actuating rod 85 is rotatably mounted by a pair of supports 86 and 87 upon the right base support flange 27, so that said rod 85 is substantially coaxially engageable at its rearward end with said plunger 82. The guard bars 83` and 84 are sutliciently close together that the actuating rod 85I cannot pass therebetween, thereby providing protection against over-travel Vof the rod 85 and resulting injury to the switch 81. The switch 81 (FIGURE 4a) may be connected to a source S of electrical energy through a starting switch 99 in a conventional manner. The rear support 86 (FIGURE 4) is a split nut, having front and rear portions 88 and 89 separated by a resilient grommet 91 and held together by a pair of adjustment screws, for the purpose of removing the backlash in the actuating rod 85. Further details regarding a split nut of this .type may be found in Patent No. 2,922,258.

The rod 85 has a calibrated, annular dial 92 (FIGURES l, 2 and 4) at the frontward end thereof and a springbacked indicator 93` supported upon the lower surface of the bottom wall 18 adjacent to said dial 92. Said rod 85 and support 86 have left hand threads, in this particular embodiment, so that clockwise rotation of the dial 92, as appearing in FIGURE l, will cause said rod to move away from the switch 81. Thus, 'by proper vadjustmen-t of the dial 92 with respect to the indicator 93 (FIGURE 2), and as a result of the anti-backlash characteristic of the support 86, the actuating rod 85 can be so located that it will engage the plunger 82 (FIGURE 4), thereby actuating the switch 81, when the table base 16 reaches a precise,k predeterminable position during lrearward movement thereof. 'Ihe accuracy of the switch Table brake A brake rod 95 (FIGURES l, 2 and 4) is rotatably supported upon the forward edge of the top plate 12 crosswise of, and just below, the actuating rod 85. Said brake rod 95 is supported by means of an inner bracket 96 (FIGURE 4), which threadedly engages said brake rod 95, and an outer bracket 97, which acts as a bearing. The leftward end of the rod 95 is engageable with the right ilange 27 of the table base 16. The outer, or rightward, end of the rod 95 is provided with a control knob 98 (FIGURE l) for tightening the brake rod 95 against the right `ange 27 and thereby locking said table base in position with respect to the frame 11.

Table angular support As shown in FIGURE 3 with respect to the left table support member 20, both the left and right support members are comprised of a hollow pedestal 101 having a concave, arcuate, upper surface 102, into which the convex, arcuate surface 103 of the quadrant 104 is slidably receivable for movement about the common axis of said convex and concave surfaces, which is the axis 23 located in the rearward edge of the table upper surface 24 adjacent to the grinding wheel 15. The quadrants 104 of the table support members 20 and 21 are slidably, but snugly, held upon their respective pedestals 101 by means, such as a post 105, which is resiliently secured to the quadrant 104 and slidably engaged by the pedestal 101 in a manner set forth in detail in Patent No. 2,922,258.

' The post 105 in the left support member 20 is provided with a bifurcated, lower end 106 which slidably engages pins 107 on a rider 108 disposed in the cavity 111 within said, pedestal 101. An adjustment screw 109, which is rotatably supported upon, and extends through, the pedestal 101, is threadedly received through said rider 108. The adjustment screw 109, which extends forwardly through the front end of the hood 17 in a direction substantially parallel with the axis of the actuating rod 85, has a control wheel 112 on its front end, whereby said screw 109 is rotated to produce the desired amount of tilting of the table 22 in the manner set forth in detail in Patent No. 2,922,258. The table 22 has a way 115 which extends crosswise thereof substantially parallel with the axis 23.

Tool holding device The tool holder 116 (FIGURES l1 and 12) is cornprised of a rectangular base frame 117, having an outer jaw flange 118 along, and extending upwardly from, one end thereof. Said base frame is provided with a symmetrical, rectangular opening 119 (FIGURE 18) therethrough near said outer jaw. Said base frame 117 also contains a slot 121 (FIGURES 13, 14 and 18), the center line f which is located along the lengthwise axis of said base frame and communicates with the opening 119 on the side of opening 119 remote from the jaw 118. A movable jaw plate 122, having an inner jaw 123 at one end thereof, is arranged upon the base frame 117 so that said inner and outer jaws are opposed to, and can be positioned substantially parallel with, each other.

As shown in FIGURES 13, 14 and 15, said jaw plate 122 has, at a point substantially spaced from the inner jaw 123, a vertical opening 124 therethrough, the upper portion of which has flat sides 124a and 124b and semicircular ends, and is elongated crosswise of said jaw plate 122. Said opening 124 also has a portion 125 (FIGURE a) near its lower end, which is elongated lengthwise of said jaw plate 122, the central vertical axes of said upper and lower portions being a single line and constituting together the axis of the opening 124. A hub 126, having an eccentric opening 127 therethrough and a ilange 128 at its upper end, is received into, and is substantially equal in diameter to the width or distance between the flat sides 124a and 124i) (FIGURE 15) of the upper portion of the crosswise opening 124. A concentric, circular washer or spacer 129 is disposed within the lower portion 125 of said opening 124 and has an outside diameter approximately equal to the width of said lower portion 125.

A sleeve 131 is slidably received through the opening 127 in said hub 126 and has a flange 132 at the upper end thereof, which rests upon the upper sur-face of the flanges 128 on said hub 126. rIhe lower end of said sleeve 131 extends slightly below the lower end of the hub 126 when said flange 132 is engaging said flange 128. A bolt 133 is received through the sleeve 131 and the washer 129, and extends substantially below the lower end thereof. Said bolt is fastened nea-r its upper end by pin 130 to said sleeve 131 and is threadedly engaged at its lower end by the nut 134 (FIGURES 13 and 14). Said nut 134 has a non-circular, cross-sectional shape (FIG- VURE 18) which is slidably, but non-rotatably, received into the slot 121 in `said base frame 1-17. Said nut 134 has a flange 135 on its lower end, and said base frame 117 is undercut adjacent to the slot 121 to provide receslses 136` and 136e, into which the flange 135 is receivab e.

The sleeve 131, hub 126 and washer 129 are so arranged and constructed that, when the nut 134 is firmly secured upon the bolt 133, thereby firmly gripping the frame 117 between the nut 134 and washer 129 (FIG- URE 14), the hub 126 can be rotated with respect to both the sleeve 131 and jaw plate 122. Also, such rotation of the hub 126, due to its eccentricity with respect to the sleeve 131, will effect a movement of frame 117 with respect to, and parallel with, plate 122. The elongated openings 124 and 125 are arranged so that said movement of the frame 117 is in a direction lengthwise of said frame whereby the jaw 118 is moved toward and away from the jaw 123.

The jaw plate 122 is provided with a circular opening 137 (FIGURES l1, 13 and 17) between the opening 124 and the inner jaw 123, which is centered upon the lengthwise axis of said jaw plate 122, which latter is further defined by the center line of the slot 121. A flanged swivel disk 138 is rotatably disposed Within the opening 137 so that its flange 139 extends under the lower surface of the jaw plate 122 and into the opening 119 in said frame 117. The lower surface of the swivel disk 138 is provided with a diametrically disposed channel 141, and the upper portion of said disk 138 is provided with a relatively narrow and elongated slot 142, which is parallel with the lengthwise extent of the channel 141 and communicates between the upper surface of said disk 138 and said channel. The portion of said disk 138 disposable within the opening 137 is provided with an annular groove 143, which has a triangular cross-section and is beveled on its upper side. A pair of adjustment pins, of which one is shown at 144 (FIGURE 14), are disposed within suitable, coaxial openings, of which one appears at 145, which extend laterally through the jaw plate 122 to communicate with the circular opening 137 near its rearward end, and are arranged and constructed to enter into the groove 143 when the disk 138 is disposed within the opening 137. Adjustment screws 146 are threadedly received into the openings for positively urging said pins 144 into said groove 143, whereby said disk 138 can be locked in place with respect to the jaw plate 122 when desired. Due to the beveled surface 147 on the upper edge of the groove 143, the pins 144 are capable of wedging the disk 138 upwardly so that its flange 139 firmly embraces the lower edge of the jaw plate 122 adjacent to the circular opening 137.

A T-shaped anchor member 148 (FIGURES 13 and 17) has its stem 149 slidably disposed within the channel 141 for movement lengthwise thereof. A stud 151 extends upwardly from, and is secured to, the stem 149 approximately midway between the ends thereof. Said stud is slidably received through the slot 142 and is threadedly engaged by a locking nut 152 at its upper end for releasably holding said stud, hence the T-member 148, with respect to the swivel disk 138. The crossbar 153 of the T-member 148 is disposed under the stem 149 and has upwardly and inwardly sloping bevels 154 and 155 (FIGURES 13 and 18) at its opposite ends. The bevels 154 and 155 are engageable, respectively, by corref spondingly beveled surfaces 156e and 157a on the gripping members 156 and 157 (FIGURE 13) located below said crossbar 1and supporting same. Said gripping members and said crossbar are all disposed within the way 115 (FIGURES 11, 12, 13 and 18) and extend under the undercut portions 158 and 159 thereof. An adjustment `or -tightening screw 161, having a shoulder 162, is slidably extendable through one of said gripping members 156 and threadedly engages the other gripping member ,157, so that said gripping members 156 and 157 can be positively and relatively urged toward each other by means of the screw l161, whereby the T-member y148 is rmly held upon the table 22. The stud 151, nut 152,

pins 144 and screws 146 serve to secure the remainder of the tool holder assembly with respect to said table 22. A calibrated quadrant 163 (FIGURES 11 and 16) is provided upon the upper surface of the jaw plate 122 adjacent to the swivel disk 138, upon which pointers 164 are mounted for cooperation with said quadrant 163. A lever 165 is mounted upon the hub 126 Ifor the purpose of rotating said hub. A tool 166 is `disposable between the jaws 123 and 118 of the tool holder `1'16.

T positioning device The tool positioner 170 (FIGURES 19 and 20) is mountable upon the work table 22 for positioning said tool 166 with respect to the grinding wheel 15. 'Ille tool positioner 178 includes a support block 171, which is wider than the upper portion of the way 115. A clamping plate 172 is disposed within the way 115 and extends under the undercut port-ions 158 and 159 thereof (FIGURE l2). A pair of bolts 173 extend through suitable, vertical openings in the support block 171 and are threadedly engaged with the clamping plate 172 for lock- .ing said support block 171 with respect to the work table 22. Said support block 171 has a substantially horizontal opening 174 crosswise thereof, in which a pivot rod 175 is rotatably and axially slidably supported. Under normal circumstances, the rod 175 will be substantially parallel with the axis of the spindle 14 for reasons appearing hereinafter.

A depth spacing bar 176 (FIGURES 19, 20 and 21) is secured, las by means of the opening 177 and set screw 178, upon the rearward end of the pivot rod 175' Vand is movable therewith through an are of approximately 180 degrees. In this particular embodiment, such arc terminates in positions of said bar substantially parallel with the upper surface of the table 22 and on opposite sides of the pivot rod 175, as indicated in broken and solid lines in FIGURE 20. An elevation pin 179 is slidably disposed within an opening 181 through the bar 176, said pin being crosswise of said bar 1'76 and said rod 175 and being located between the ends of said bar. Said pin 179 is adjustably held within the opening 181 by means of a lock bolt 182, which is threadedly received 4into a lengthwise opening 183 through the bar 176 and a part of the rod 175. A lateral spacing bar 184 (FIGURES 19 and 20), having a lengthwise slot 185 therethrough, is adjustably mounted upon the `front surtace of the depth spacing bar 176 near the iiree end thereof by means of a bolt `187, which extends through the slot 185 and `is threadedly received into said bar 176.

The tool 166 is engaged by the front surface `186 (FIGURE 19) of the bar 176, and/or the outer, end surface 188 (FIGURE 23) of .the lateral spacing bar 184, in a manner discussed in detail hereinafter, for the purpose of locating said tool within a tool holder, such as that shown at 116 in FIGURES 1l and '12.

An adjustment knob 189 (FIGURES 19 and 22) has a threaded opening 191 therethrough and is threadedly received upon the threaded frontward end 192 of the pivot rod `175. The front end 192 of said rod is split by means of a lengthwise groove 193, the outer end of which groove is enlarged ,and internally threaded for receiving a lock -bolt `194. Means, such as a ball 195, is provided in said groove 193 at the inner, tapered end f196 of the enlarged portion lfor engagement by the bolt 194, whereby the front end 192 o-f the rod 175 is spread, thereby locking the knob 189 upon the rod 175. The parts of said tool positioner 170 `are so arranged that, when said support `block 171 is mounted upon the work table 22, said depth spacing bar 176 can be moved by fthe rod 175 from a position wherein its front surface 186 can be disposed both rearwardly and frontw-ardly of the rearward edge 23 of said table 22.

ALTERNATE STRUCTURE The power cylinder 714, shown in FIGURE 4, may be replaced quickly and easily by the rod 200 (FIGURE 10), which has a bifurcated, front end 205 pivotally' mounted upon the larm 72 and has a portion 20-1 ot' re-Y duced diameter at its rearward end, which is slidably received in a guide opening y202 in the bracket 76. A spiral spring 283 is sleeved upon the rod 200 between the frontward wall of the bracket 76 and the shoulder 204 provided by the bifurcated frontward end 205 of said rod 200.

OPERATION As stated previously, the Itool grinder 10 described hereinabove may be quickly and easily adapted for fully automatic operation, semi-automatic operation or fully lmanual operation, such interchangeability being an Iintegral part of the structure of the machine. For a more complete disclosure of the operation of the tool grinder, its fully automatic operation will be described rst.

Under normal circumstances, the tool holder or vise 116 (FIGURES l1 and 12) is first mounted upon the upper surface 24 of the work table 22, with the crossbar 15'3 of the T-member 148 disposed within the way 115, between the gripping members 156 and 157. The screw 161 is then turned until the gripping members seize the bar 153, `thereby locking the T-member 148 w-ith respect to the work table 22. The bolt 133, the adjustment screws 146 and the stud nut 152 are loosened thereby permitting lengthwise -movement of the jaw plate 122 with respect :to the base frame I117 and pivotal movement of both the jaw plate |122 and base frame 117 with respect to the T-member 148. Thus, the jaws 1'18 and 123 -can be opened and closed, and then swiveled around as desired upon the work table 22.

Assuming, for the purposes of illustration, that the tool 166 (FIGURE 19) has its cutting edge 167 at one end thereof and substantially perpendicular to the lengthwise extent thereof, the vise 116 will be swiveled into `a position wherein the jaws 118 and 123 are substantially transverse of the way 115. Referring to FIGURES 17 and 18, it will be seen that, since the stemy 149 is disposed within the channel 141 in the disk 138, the jaw plate 122 will swivel around the disk 138. However, in order to swivel the jaw plate 122 into its FIGURE 11 position, the steml 149 must be substantially completely within the disk 138. Otherwise, said stem will strike the walls of the opening 119 in the frame 117. Accordingly, transverse movement of the T-member 148 (and likewise of the disk 138 and plate 122) with respect to the frame 117 is somewhat limited when the vise is in the FIGURE 11 position. However, since the tool 166 can itself be moved in this direction, lengthwise of the jaws 118 and 123, no problem` is encountered.

When the frame 117 and T-member 148 are in their FIGURE 18 positions with respect to the way 115, transverse movement ot the T-member with respect to the frame 117 is even further restricted. However, this is overcome by the fact that the entire vise can be moved along the Way by manipulating the screw 161 (FIG- URE 11). On the 4other hand the T-member 148, when in the FIGURE 18 position, can be moved very substantially lengthwise of the frame 117, because of the combined length of the opening 119 and slot V121. Intermediate, angular positions of the frame 117 with respect tot the T-member 148, as shown in FIGURE 16, will permit some lateral and some lengthwise relative movement in varying amounts, depending upon the positions of these members. After the vise 116 is properly located on the table 22, the tool 166 is then placed between the jaws 118 and 123, after which the base frame 117 is slidably moved manually with respect tot the plate 122 until the jaw 118 causes the tool 166 tobe engaged by the inner jaw 123. The nuts 152 and 134 are then snuggedup, but not finally tightened.

Inasmuch as the initial positioning of the T-member 148 with respect to the table 22 is approximate at best, the screw 161 (FIGURES 1l and 13) is now loosened l1 and the entire tool vise 116 is moved along the way 115 until the center line of the tool 166 substantially intersects the center of reciprocation of the grinding surface on the wheel 15, where said wheel will be engaging said tool. The screw 161 is now tightened and it will be unnecessary to touch it again until the particular job is complete. The nut 152 may now be loosened on the stud 151 and final, relatively minor, adjustments made in the position of the tool 166, as indicated by the pointers 164, so that its cutting edge will be properly aligned with the adjacent surface of the grinding wheel for the desired grinding operation, after which the nut 152 is secured in position. The bolt 133 is then firmly secured with respect to the nut 134. Because of the fact that the sleeve 131 is slightly longer than the hub 126, said hub can be turned with respect to, and upon, the sleeve 131, thereby effecting relative movement between the frame 117 and plate 122.

After the bolt 133 (FIGURE 13) is tightened securely in position, the hub 126 is rotated by means of the lever 165 thereon so that the eccentricity of said hub causes the frame 117, hence the outer jaw 118, to move away from the jaw plate 122. This permits lengthwise movement of the tool 166 within the vise 116. The actuating rod 85 is adjusted so that it will engage the plunger 82 on the switch 81, thereby reversing the power cylinder 74 before the table 22 reaches its full rearward position, as determined by the limit device 62. The distance between the point where the switch is closed and the point at which the table reaches its said full rearward position is arranged to be in excess of the distance the table will have to move in order to cut olf the desired amount of metal from the tool being ground.

The power cylinder 74 (FIGURE 4) is now energized, thereby causing the table 22 (FIGURE 2) to move rearwardly toward the grinding, wheel 15 until it reaches the position where the switch 81 is closed by the actuating rod 85. When the table 22 reaches this position, the tool 166 is moved rearwardly between the jaws 118 and l123 until it touches the grinding surface of the wheel, after which said tool is firmly locked in the vise 116 by rotating the hub 126 in the appropriate direction by means of the lever 165. The actuating rod 85 is now rotated and backed away from the electric switch 81, as indicated by the dial 92, a distance equal to the exact depth of metal to be removed from the cutting edge 167 of said tool. Thus, when the power cylinder 74 is again energized, said table 22 will move rearwardly until the desired amount of metal is removed from the tool, before the switch 81 is actuated and the urging of the table is reversed in its direction.

Ordinarily, the tool `grinder 10 is arranged for automatic operation when there are a number of substantially identical tools to be ground in substantially the same manner. Thus, having taken this time to set the tool 166 within the vise 116, it becomes advantageous to determine the position of the tool within said vise in such a manner that further, similar tools being held within the vise can be positioned at exactly the same location with respect to said grinding wheel.

To accomplish this, the tool positioner 170 (FIGURE 19) is mounted upon the work table 22 in the manner described hereinabove, while the table 22 is in its forward position and spaced from the grinding wheel 15. The lock bolt 194 is loosened, thereby permitting the `adjustment knob 189 to be rotated and thus advanced along the pivot rod 175. The bolts 173 are loosened, thereby permitting movement of the tool positioner 170 along the way 115 until the bar 176 is adjacent to the cutting edge 167. The pivot rod 175 is moved through the support block 171 until the front surface 186 of the bar 176 is snugly against the cutting edge 167 of the tool 166. The bolts 173 are firmly tightened into the clamping plate 172, whereby the tool positioner 170 is locked against movement lengthwise of the way 115. The adljustment knob 189 is now moved along the rod 175 until it firmly engages the adjacent side of the support block 171, thereby holding the depth spacing bar 176 firmly against the tool edge 167. The lock bolt 194 is then tightened, thereby locking the adjustment knob in position, as desired. The tool positioner 170 is now adjusted for positioning additional tools in the vise 116 for a similar grinding operation.

In order to grind a tool so positioned, the depth spacing bar 176 is rotated by the rod 175 from its solid line position into its broken line position (FIGURE 20) and then moved frontwardly, away from any possible interference with the grinding wheel 15. The tool grinder is now in condition for effecting a grinding of the tool 166 held Within the vise 116.

The power cylinder 74 (FIGURE 4) is energized by closing the conventional starting switch 99 on the machine, thereby causing the piston rod 75 to draw the table 22 rearwardly toward the grinding wheel. The table 22 will move in a rearward direction until the grinding operation is complete. At this point the switch 81 is actuated -by the actuating rod 85, thereby reversing the flow of pressure fluid through the power cylinder 74 and returning said table 22 to the forward position for reloading.

Reloading of the vise 116 (FIGURE ll) is accomplished quickly and easily by first rotating the hub 126 by means of the lever until the jaws of the vise 116 release the tool 166, which is then removed from said vise. Another tool requiring the same operation is then placed in the vise, after which the depth spacing bar 176 is again moved over into position in front of the tool and moved as far forwardly as the adjustment knob 189 will permit. The new tool 166 is then moved snugly up against the front surface 186 of the bar 176, after which the hub 126 is again rotated until the jaws of the vise 116 firmly grip and hold the new tool. The bar 176 is again moved out of its position in front of the tool, in the same manner as described hereinabove, after which the power cylinder 74 is again energized to effect a second operation of the machine 10.

Where it becomes necessary to grind a tool having a cutting edge 167 which, for example, is substantially along its lateral side, as shown in FIGURE 23, the tool holder 116 is mounted upon the table 22 so that the jaws thereof are substantially parallel with the way 115. In such position the frame 117 (FIGURE 18) can move a substantial distance with respect to the T-member 148, toward and away from the wheel 15. For this type of grinding operation, both the depth spacing bar 176 and the lateral spacing bar 184 on the tool positioner 170 are used to position additional tools after the rst one is properly positioned. The bolt 187 and slot 185 provide for adjustment of the bar 184. In order to position a tool within the vise 116, the jaws and stud nut 152 thereof must be loosened and the device rotated into its operative position as shown in solid lines in FIGURE 20. The new tool is placed within the jaws 118 and 123 and moved leftwardly (FIGURE 23) until it engages the bar 184. The jaws are now tightened by means of the hub 126 but the stud nut 152 is still loose. Both jaws and the frame structure associated therewith are now moved forwardly (disk 138 sliding on stem 149) until the cutting edge 167 of the tool engages the front surface 186 of the depth bar 176, while the tool is still engaging the bar 184. The stem 149, which is disposed in the groove 141 of disk 138, prevents other than lengthwise movement of the frame structure during said movement thereof. The nut 152 is now tightened and the grinding operation may be commenced.

Under some circumstances, it may be necessary or desirable to tilt the table 22 out of a substantially horizontal position. This is easily accomplished by turning the wheel 1.12 (FIGURES 2 and 3), which, being secured to the adjustment screw 109, causes the post 105 to pivot with the quadrant 104 upon the pedestal 101 of the table support member 20. The table 22, which is supported upon said quadrant 104, is thus tilted, either upwardly or downwardly, with respect to the horizontal position and about the table pivot axis 23. This, however, will have no material `effect upon the above-described operation of either the tool vise 116 or the tool positioner 170.

It will be seen that complex angles of the cutting edge 167 on said tool 166 can be provided by tilting the table 22 and by mounting the tool holder 116 at an angle to the way 115, such as shown in FIGURE 16. As stated above, pivotal movement of the vise 116 to obtain such adjustment can be effected by loosening the nut 152 and the adjustment `screws 146, thereby permitting a rotational movement of the jaw plate 122 about the swivel disk 138 within the circular opening 137. If the same jaw opening will be utilized after the vise 116 is repositioned, it is unnecessary to loosen the nut 134 on the bolt 133 during such pivotal movement of the vise 116. After the proper angular relationship is obtained, as indicated by the' pointers 164 and calibrated quadrant 163 on top of the swivel disk 138 and jaw plate 122, respectively, the adjustment screws 146 and stud nut 152 are again tightened, thereby locking the tool vise 116 in the new position.

Semi-automatic operation As used herein, semi-automatic operation pertains to a manual urging of the table 22 toward the grinding wheel 15, after which resilient means associated with the table 22 automatically returns said table to the frontward position, away from said grinding wheel. In this particular embodiment, such automatic return is accomplished by exchanging the power cylinder 74 (FIGURE 4) for the the tool vise 116 may be utilized for holding the tool in position during the grinding operation and the tool positioner 170 may be utilized for locating additional tools to be ground in substantially the same manner. However, the use-of other tool holders and/ or positioners is possible without alecting the operation of the table movement. Nevertheless, the use of some type of tool vise is advantageous in semi-automatic operation. Where the tool positioner `170 is utilized, lit can be coordinated with the limit device 62 (FIGURE 8) so that a predetermined amount of the tool being ground will be removed before the rearward movement of the table 22 is stopped by the limitV device 62. Frontwardmovement of the table 22 by the spiral spring 203 will be terminated by the limit device 61 (FIGURE '7).

Fully manual operation I tfIn the fully manual operation, neither the power cylinder 74 nor the spring and rod arrangement 200 are used. In such case, the table 22 is positioned as desired with 'respect to the grinding wheel, the limit devices being released as necessary, and the table 22 then locked in a iixed :position with respect tothe support frame 11 by turning the brake rod `95 (FIGURES l and 4) until it tightly grips the right base support ange 27 on the table base 16. The tool or other workpiece being ground can then be hand fed ac`r`o's`s the surface of the table 22and against the grinding -wheel in a substantially conventional manner. Neither the tool vise 116 nor the tool positioner 170 will normally'be used under these conditions and may be removed if desired. However, in hthis case, as well as all `of the other above-mentioned circumstances of operation,

fthe grinding wheel 15 will oscil'late radially of its axis in a `substantially horizontal .path with `respect to the table 22, thereby providing the operational advantages discussed in detail in Patent No. 2,922,25 8.

, 14 Although particular, preferred embodiments of the in: vention have been described in detail hereinabove for illustrative purposes, it will be recognized that modifications or variations thereof, which do not depart from the scope of such disclosure, are fully contemplated unless specically stated to the contrary in the appended claims.

What is claimed is:

l. A grinding machine comprising: a support frame; a radially oscillatable grinding wheel mounted upon said iframe; a hood surrounding said grinding wheel, said hood having a bottom wall and upstanding side and end walls below said grinding wheel defining a trough extending forwardly from and located below said grinding wheel, said trough having an open upper end; a plurality of upstanding table support members extending upwardly from said bottom wall, said table support members including means defining an arcuate upwardly facing edge; a work table having an inner edge adjacent said grinding wheel and extending transverse to the axis of rotation thereof, said table having a downwardly extending arcuate member matingly engaging said arcuate edge so that said table is supported Afor rocking movement about an axis delined by said inner edge; a post extending downwardly from said arcuate member; means engaging said post for moving same toward and away from said grinding wheel to thereby rock said table about said axis; a rotatable shaft -for moving said last-named means; shaft engaging means supporting said shaft for rotation around an axis transverse of said inner edge and thereby moving said post and rocking said table; and means mounted on said support frame and loca-ted below said bottom wall for moving said table toward and away from said grinding wheel.

2. A grinding machine according to claim l wherein said support frame includes horizontal, stationary, support members extending forwardly with respect to said grinding wheel below said trough; a table base located between said support members and said trough; bearings supporting said table base on said support members for reciprocable movement with respect thereto toward and away from said grinding wheel, said table base being secured to said table support members for causing corresponding movement thereof; said means for moving said table ltoward and away from said grinding wheel being connected to said table base.

3. A grinding machine according to claim 2 wherein said means for moving said table includes a fluid pressure operated piston and cylinder, said piston being connected to one and said cylinder being connected to the otherv of said frame and said table base; a source of fluid pressure for operating said piston and cylinder; a yswitch mounted on said support -frame and connected for controlling supply of uid pressure to said piston and cylinder; a switch actuator mounted on said table base and engageable with said switch to reverse the supply of fluid pressure to said piston and cylinder when said table is a predetermined distance away from said grinding wheel to cause said table to be moved away from said grinding wheel.

4. A grinding machine according to claim 3 wherein said switch actuator is a threaded shaft rotatably mounted on said table base for adjustment toward and away from said switch; and means for rotating said shaft to adjust the distance between Same and said switch to thereby determine the point at which movement of said table toward said grinding wheel is stopped.

5. A grinding machine according to claim 2 including a plurality of interengageable, adjustable stop devices on said table base and on said support members for limiting movement of said table base and thereby said table toward and away from said grinding wheel.

6. A grinding machine comprising: a support frame; a radially oscillatable grinding wheel mounted upon said frame; a hood surrounding said grinding wheel, said hood havinga bottom wall and upstanding side and end walls below said grinding wheel defining a trough extending forwardly from and located below said grinding wheel, said trough having an open upper end; a plurality of upstanding table support members extending upwardly from said bottom wall, said table support members including means defining an arcuate upwardly facing edge; a work table having an inner edge adjacentV said grinding wheel and extending transverse to the axis of rotation thereof, said table having a downwardly extending arcuate member matingly engaging said arcuate edge so that said table is supported for rocking movement about an axis defined by said inner edge; said support frameV including a movable table base, said table base having a pair of spaced, table support flanges on the upper surface thereof, a pair of parallel, spaced, guide anges located inwardly from said table support flanges and extending downwardly from the lower surface of said table base, said guide flanges having guideways formed therein extending toward said grinding wheel, said table base having an upwardly arched portion between Said guide flanges defining a recess extending toward said grinding wheel; said support frame including a stationary support structure having a pair of parallel support bars, each of which is adjacent and opposed to one of said guide flanges, said support bars having guideways therein opposed, respectively, to the guideways in said guide flanges; ball bearing means between said guideways and supporting said table base and said table for movement toward and away from said grinding wheel; and actuating means disposed in said recess and between said support bars and connected at one end thereof to said support structure and connected at the other end thereof to said table base for moving said table base andsaid table toward and away from said grinding wheel.

7. A grinding machine comprising: a support frame; a radially oscillatable grinding wheel mounted upon said frame; a hood surrounding said grinding wheel, saidhood having a bottom wall and upstanding side and end walls below said grinding wheel defining a trough extending forwardly from and located below said grinding wheel, said trough having an open upper end; a plurality of upstanding table support members extendingupwardly from said bottom wall, said table support members including means defining an arcuate upwardly facing edge; a work table having an inner edge adjacent said grinding wheel and extending transverse to the axis of`rotation thereof, said table having a downwardly extending arcuate member matingly engaging said arcuate edge so that said table is supported for rocking movement about an axis defined by said inner edge; Said support frame including a movable table base, said table base having a pair of spaced, table support flanges on the upper surface thereof, a pair of parallel, spaced, guide flanges extending downwardly from the lower surface of said table base, said guide flanges having guideways formed therein extending toward said grinding wheel, said table base having an upwardly arched portion between said guide fianges defining a recess extending toward said grinding wheel; said support frame including a stationary support structure having a pair of parallel support bars,

each of which is adjacent and opposed to one of said guide flanges, said support bars having guideways therein opposed, respectively, to the guideways in said guide flanges; ball bearing means between said guideways and supporting said table base and said table formovement toward and away `from said grinding Wheel; and actuating means disposed in said recess and between said support bars and connected at one end thereof to said support structure and connected at the other end thereof to said table base for moving said table base and said table with respect to said grinding wheel in a direction substantially parallel with the rotational axis of said grinding wheel.

8. The structure of claim 7 including adjustable means .operatively `associated with Lsaid stationary support struc- 1-6 ture and with said table base for selectively and positively limiting said movement of said table base toward and, away from the grinding wheel.

9. The structure of claim 7 wherein said actuating' i means includes a resiliently compressible member arranged and compressed between said stationary support structure and said table base whereby said table base is continuously and resiliently urged away from said grinding wheel.

10. The structure of claim 7 wherein said actuatingI means includes a power cylinder connected between said support structure and said table base, a source of pressure fluid connected to said power cylinder for effecting positive reciprocation thereof, and operatively engageable control means on said support structure and said table base for controlling the ow of pressure uid between said source and said power cylinder in response to said move/ ment of said table base with respect to the grinding wheel.-

1l. The structure of claim 7 wherein said actuating means includes a pressure fluid operated power cylinder, a source of pressure fluid, electrical switch means mounted upon one of said support structure and said table base for controlling the flow of pressure fluid between said source land said power cylinder, and a switch operator mounted upon the other of said support structure and table base operatively engageable with said switch in response to said movement of said table base, whereby said movement of said table base with respect to said grinding wheel is automatically controlled.

12. A grinding machine comprising: a support frame; a grinding wheel mounted upon said frame; a trough extending forwardly from and located below said grinding wheel, said trough having a bottom wall and an open upper end; an upstanding table support member extending upwardly from said bottom wall, said table support member including means defining an arcuate upwardly facing edge; a work table having `au inner edge adjacent said grinding wheel and extending transverse to the axis of rotation thereof, said table having a downwardly extending arcuate member matingly engaging said arcuate edge so that said table is supported for rocking movement about an axis defined by said inner edge; a movable table base having a trough support member on the upper surface thereof and a pair of parallel, spaced, guide flanges extending downwardly from said table base, said guide flanges having first guideways formed therein extending toward said grinding wheel, said table base having an upwardly arched portion between said guide flanges defining a recess extending toward said grinding wheel; said support frame including a stationary support structure having a pair of parallel support bars, each of which is adjacent and opposed to one of said guide anges, said support bars having second guideways therein opposed, respectively, to the rst guideways in said guide flanges; said first guideways being operatively mounted upon and movable lengthwise along said second guideways, whereby said table base and said table are movable toward and away from said grindng wheel; and actuatng means disposed in said recess and between said support bars and connected at one `end thereof to said vsupport structure and connected at the other end thereof to said table base for moving said table base and said table with respect to said grinding wheel in a direction substantially parallel with the rotational axis of said grinding wheel.

References Cited in the file of this patent UNITED STATES PATENTS 587,537 Van Norman Aug. 3, 1897 976,270 Leonard Nov. 22, 1910 1,032,758 Lumsden July 16, 1912 1,084,489 Schmutz Jan. 13, 1914 1,193,525 Dosch et al. Aug. 8, 1916 (Other references on following page) UNITED STATES PATENTS Mallory Aug. 22, 19'16 Sann Apr. 3, 1928 Bangser Feb. 23, 1932 Tebbe Oct. 10, 1933 Yassenoff June 19, 1934 18 Maglott Aug. 23, 1938 Oliver Aug. 12, 1941 Selnes May 14, 1946 Metz Nov. 8, 1955 Falls Apr. 17, 1956 

